Although the present invention can be used with all desired data transmission technologies, it is explained here together with the problems on which it is based from the standpoint of mobile wireless technology.
There are various conventional technologies for multichannel wireless transmission, in particular TDMA (time division multiple access), e.g., GSM (global system for mobile telecommunications) or UMTS (universal mobile telecommunication system), FDMA (frequency division multiple access), e.g., DECT (digital enhanced telecommunication), GSM (global system for mobile telecommunications), DAB (digital audio broadcasting) and CDMA (code division multiple access) (IS95, UMTS).
Problematic interference which can occur with these different technologies is usually handled in different ways, if at all. In particular, conventional methods include elimination of intersymbol interference (ISI), elimination of multiple access interference (MAI), elimination of interference in the receiver, e.g., by equalizers or multiuser methods or joint detection methods, as well as elimination in the sender by pre-rake or joint preliminary equalization. See, for example, K. D. Kammeyer, “Nachrichtenübertragung [Transmission of Communications],” 2nd edition, Information Technology Series, Teubner, Stuttgart, 1996, and A. Klein, G. K. Kaleh and P. W. Baier, “Zero Forcing and Minimum Mean-Square-Error Equalization for Multiuser Detection in Code-Division Multiple-Access Channels,” IEEE Trans. Vehic. Tech., vol. 45 (1996), 276–287 and R. Esmailzadeh and M. Nakagawa, “Pre-Rake Diversity Combination for Direct Sequence Spread Spectrum Mobile Communications Systems,” IEICE Trans. Comm., vol. E76-B (1993), 1008–1015.
In addition, different parameters are generally used under different transmission conditions, e.g., in the UMTS TDD mode, where different types of bursts are used, depending on the maximum channel delay. In this regard, see, the example, the UMTS-L1 expert group: “UTRA Physical Layer Description, TDD parts, V 0.2.0.”
One disadvantage of the conventional approaches is that a transmission technology having a given set of parameters is more advantageous than another transmission technology only under certain transmission conditions or with certain transmission properties of the data transmission channel.
Therefore, it may occur that an unnecessarily low transmission quality prevails under certain transmission conditions or there may be an unnecessarily great dependence of transmission quality on transmission conditions.
It would thus be desirable to create a data transmission system which can always guarantee optimum transmission quality, regardless of whether data transmission conditions are variable or constant.